1. Field of the Invention
The invention relates generally to the multiplication and mass production of an entomophagous insect such as Trichogramma maidis, from a substitution host such as the egg of the meal moth Ephestia kuehniella, said entomophagous being in this case released in seasonal inundatory batches in the biological fight against a maize crop ravager, Ostrinia nubilalis or maize meal moth.
The invention relates then more particulary to a method for the mass production of an entomophagous insect with a device for implementation thereof, as well as the application of said method to the biological struggle using microcontainers intended for in the field release.
2. Description of the Prior Art
In the case of Trichogrammides, the production of this entomophagous insect has been achieved up to now in so called "multiplication" cages where host eggs are presented in a monolayer on plates to a quantity of adult Trichogrammides, or inoculum, in a ratio of 10/1 and previously emerged from parasitized eggs disposed loose in the cage.
When it is necessary to provide cold storage before using the parasitized eggs, the duration of the parasitism of the host eggs by inoculum of Trichogrammides must be limited to 48 hours at 25.degree. C. (compare work of Madame PIZZOL on the induction of the diapause in Trichogramma maidis allowing this cold storage). On average, 75% of the host eggs thus presented are parasitized. A part of the eggs thus parasitized is however recyled as inoculum for the next generation.
This method of multiplication in cages for 24 to 48 hours has certain drawbacks:
1.degree. Handling of numerous cages without great possibility of automation;
2.degree. Partial use of the laying potential of the Trichogrammide females, the parasitism being at most 48 hours at 25.degree. C., minimum condition indispensable for a correct rate of induction of diapause of the Trichogrammide lavae before cold storage.
The parasitism time of the part recycled as inoculum must not exceed 48 hours either so as to avoid too great a staggering of the emergences in the cages. Even in this case, it is then necessary to wait for at least 48 hours after the first emergences of the inoculum so as to introduce the tray of host eggs.
The present invention aims then at overcoming these drawbacks, by providing a method of multiplication and mass production of entomophagous insects by formation of host eggs parasitized in a population cage, finding an advantageous application in the case of Trichogrammides and in the biological fight against the maize meal moth.